Stabilization of metal soap solutions in oil



Patented May 6, 1941 STABILIZATION F METAL soar SOLUTIONS IN OIL ThomasE. Sharp, Chicago, 111., assignor to Standard Oil Company, Chicago,111., a corporation of Indiana No Drawing. Application June 7,1939,

Serial N0. 277,905

6 Claims.

This invention relates to the stabilization of metal soap solutions withoil andit pertains more particularly to the stabilization of solubleoils containing aluminum oleate.

So-called soluble oils are oils which contain oil-soluble emulsifiers sothat when they are added to water with or without a certain amount ofstirring they readily emulsify. A very important soluble oilparticularly for use in tree sprays is a white oil (or parafilndistillate of high unsulfonatable residue) containing about /2 to 4%,preferably 2 of aluminum oleate, usually with a smaller amount of ahydroxy ester of a high molecular weight organic acid such as glycerylmono-oleate or glycol mono-oleate. The aluminum soap may be made from arelatively pure oleic acid or it may be made from commercial grades ofoleic acids obtained by thesplitting of fats, cottonseed oil, etc. Sucha soluble oil may for instance have the following formula:

Per cent White oil 96 Aluminum cottonseed soap (aluminum oleate) 2 /2Glyceryl mono-oleate 1 /2 When soluble Oils of the above type are storedover-extended periods of time an insoluble resinfact is thatoutstandingly good antioxidants like alpha naphthol are not nearly aseffective as the above compounds for preventing soap separation.Outstanding antioxidants such as ortho-phenylene diamine, salicylaldehyde amine, etc. areentirely inefiective,soluble oils containingthem become very cloudy and are badly precipitated. It appears that theproblem of maintaining the soap in solution is a very different problemthan that of stabilizing the white oil against oxidation not onlybecause most antioxidants are inoperative, but because the separationproblem with which the present invention is concerned leads to theprecipitation of a fiocculent material which is entirely different fromthe product resulting from white oil oxidation.

The invention will be described as applied to soluble oils for use intree sprays, but it should be understood that the invention is equallyapous material separates from the oil. The exact chemical composition ofthis resinous material has not as yet been determined, but it appears tobe a polymerized metallic soap or some compound of a metallic soapformed from a combination with the glyceryl mono-oleate.

These resinous deposits separate out to such an extent that the solubleoil becomes quite opaque with fiocculent precipitates which separateout, thereby rendering the oil commercially unsalable. The object ofthis invention is to provide a method and means for preventing theseparation of these resinous deposits. A further object is to I providean improved soluble oil containing alumitoxic materials such as derrisand rotenone,-the

plicable to soluble oils containing aluminum soaps and used for otherindustrial purposes. aluminum soap may be prepared from any fat or fattya'cideither of animal, vegetable or synthetic origin. The aluminum soapmay be present in amounts ranging from about /2 to 4% and it may besupplemented by about /2 to 3 or 4% of glyceryl oleate, glycerylmono-oleate, glycol oleate, diglyool oleate, glycol .mono-oleate, etc.The oil may be an ordinary paramn distillate such as straw oil, diamondparaflin oil, etc., or it may be a more refined technical white oil or arelatively pure grade of white oil. The viscosity of the oils may rangefrom that of Mineral Seal (about 40 to 50 seconds Saybolt at 100 F.) tofairly heavy oils ranging in viscoslties from to 120 seconds Saybolt atF. and for some industrial purposes even more viscous oils may be used.

Although the preferred soaps are aluminum oleates, it should beunderstood that the invention is also applicable to aluminum stearates,palmitates, naphthenates, etc., particularly when these soaps areemployed with glyceryl oleate, glyceryl naphthenate and similar esters.

Of the substituted phenol compounds I have found that beta naphthol isparticularly effective. Guaiacol (mono methyl ether of catechol) notonly prevents soap separation but maintains an even higher degree ofcolor stability than beta naphthol. Octyl beta naphthol and tertiarybutyl catechol have given excellent results both from the standpoint ofpreventing soap separation and from the standpoint of color stability.It will thus be seen that the phenol maybe substituted by an aryl orcyclic group as exemplified The by beta naphthol. This cyclic group maybe entirely independent of the ring structure of the phenol, asillustrated by cyclo hexyl catechol. The substituting radical may be analkyl radical as illustrated by octyl beta naphthol. The substitutinggroups on the phenol may comprise both alkyl and hydroxy radicals asexemplified by tertiary butyl catechol. The substituting group may be anether instead of an alkyl or OH group as illustrated by guaiacol.Broadly speaking, therefore, the invention contemplates the use ofsubstituted phenols although the preferred embodiments of the inventionare the specific compounds hereinabove set forth.

The substituted phenols must be used in critically small amounts,preferably ranging from about .05% to .1%, although slightly more orless, i. e. from a trace to about .5% of the substituted phenols may beused for particular purposes without departing from the invention. Apreferred example of the invention is a soluble oil with the followingformula:

When the above oils were stored at temperatures of 130 F. they stood formonths without,

any soap separation and without going off color. However, when the sameformulae were stored under these conditions without the substitutedphenol the soap separated out in less than two weeks.

The outstanding stabilizer against soap separation is beta naphthol oran alkyl substituted beta naphthol such as octyl beta naphthol or amylbeta naphthol.

The outstanding examples of soaps requiring stabilization are aluminumoleates, stearates, etc. as hereinabove described. It should beunderstood, however, that the invention may be applied to thestabilization of soluble oils containing other polyvalent metal soaps orheavy'metal soaps such as soaps of zinc, magnesium, iron,

lead, etc. The invention is, of course, only applicable to those soapswhich separate out from soluble oil solutions in the form of resinousdeposits or flocculent precipitates, a phenomenon which is altogetherseparate and distinct from the stabilization of solid or semi-solidgreases against oil leakage.

While I have described in detail preferred embodiments of my inventionit should be understood that the invention is-not limited to theparticular compounds listedthe broad classes of compounds has been setforth and the use of other members of these classes will be apparent tothose skilled in the art.

I claim:

1. An improved soluble oil of about the following formula:

Percent Oil 95.9 to 95.95 Aluminum soap 2 /2 Glyceryl mono-oleate 1 Betanaphthol .05 to.1

2. The method of stabilizing a tree spray oil of about the followingcomposition:

- Percent White oil 96 Aluminum soap 2 Glyceryl mono-oleate 1% againstsoap separation on standing, which method comprises adding to said treespray oil about .05 to .1% of a beta naphthol compound.

3. The method of claim 2 wherein the compound is unsubstituted betanaphthol.

4. The method of claim 2 wherein the compound is an alkyl substitutedbeta naphthol.

5. The method of preventing soap separation from soluble oils containingan oil soluble polyvalent metal soap and an ester of the classconsisting of glycol and glyceryl esters of high molecular weightorganic acids said ester containing insufficient amounts of the acidconstituent to be completely esterified, which method comprises addingto a solution of said soap and said ester in said oil about .05 to .1%of a substituted phenol of the class consisting of beta naphthol, analkyl beta naphthol, guaiacol and a lower alkyl catechol.

6. The method of claim 5 wherein the soluble oil contains about to 4% ofan aluminum soap and about A; to 4% of the ester.

THOMAS E. SHARP.

